Motor control system



Oct. 12,1937.-

WITNESSES: I mvanTqR g4 77;; MflmmEE/m/erm W. R. TALIAFERRO MOTOR CONTROL SYSTEM Filed March 5, 1936 2 Sheets-Sheet l Oct. 12, 1937. -w. R. TALIAFERRO 2,

MoTbR CONTROL SYSTEM Filed March 5, 1936 2 Sheets-Sheet 2 WITNESSES:

e INVENTOR 73/[0/6/7'0 UNITED STATES PATENT OFFICE,

2,095," 3 MOTOR CONTROL SYSTEM William R. Taliai'crro, Pittsburgh, Pa.,

to Westinghouse Electric &' Manufacturing Company, East Pittsburgh, Pa., a corporation oi Pennsylvania Application March 5, 1936, Serial No. 67,287

'5 Claims. (c1.171 119) cally-propelled vehicles.

Heretofore, the speed of an alternating-current locomotive has usually ing the taps on the 10 tion of a locomotive.

been controlled by changw tension side of a locoby means of unit switches An object of my invention, generally stated, is

to provide a control which shall be simple and which may be cc and installed.

system for. electric motors and eflicient in operation onomically manufactured A more specific object of my invention is to prevent interrupting the power circuit of a locomotive control system by means of tap-changing switches.

Another object of a locomotive control changing operations 4 tension winding of a my invention is to provide system in which the tapare performed on the hightransformer;

Other objects of the invention will be explained fully hereinafter or skilled in the art.

will be apparent to those According to one embodiment of the inven- 'tion, small, light and inexpensive switches are utilized for tap-changing instead of the large and heavy circuit-breaking switches previously used.

the power circuit, the

performed by electronic nately made conducting The tap-changing nected in the system that switches are so conthey never interrupt rupturing duty being devices which are alterand non-conducting by are controlling the energization of the control elements of the electronic devices.

In this manner the following detailed description, taken in conjunction with the accompanying drawings, in

which:

Figure 1 is a diagrammatic view of a control system embodying the invention; and

principal features of the Fig. 2 is also a diagrammatic view of a modified form of the invention.

Referring to Fig. 1 of the shown comprises a motor In, a transformer ll having a primary winding 1 2 and a secondary 5 winding IS, a preventive coil [4 and an autodrawings, the system 20 the transformer IS in sequential relation. A master controller MC is provided for controlling the operation of the tap-changing switches l to l in a manner which will be more fully described hereinafter.

As stated hereinbefore, in previously known locomotive control systems the tap-changing switches have been required to open and close the power circuit while current is flowing to the motors, thereby making it necessary to so construct the tap-changing switches that they are capable of performing arc rupturing duty. In the present system, I have provided a plurality of ignitioncontrolled mercury-cathode electronic devices 2| to 24, inclusive, which are so connected in the power system that the tap-changing switches l to I, inclusive, are prevented from closing or opening the power circuit while current is flowing to the motor Ill. Since the arc rupturing duty is performed by the electronic devices, the tapchanging switches may be of a cheaper and lighter construction, thereby effecting a saving in the cost of the locomotive equipment as well as in the space required for the equipment.

Each one of the electronic devices 2| to 24 comprises an anode 25 and a mercury cathode 25. The control function for the device is per formed by an electrode 27, generally called an igniter, the end of which is disposed in the mercury cathode 26 as shown. The characteristics of the electronic device are such that no current will flow from the anode 25 to the cathode 26 until operation of the device is started by energizing the igniter 27. After the device is started, current will continue to flow during the positive half cycle, but is automatically extinguished at the end of the half cycle and the igniter must be energized at the beginning of the next positive half cycle in order to restart the device.

As shown, the electronic devices 2| and 22 are so connected that the device 2| permits current to fiow during one half of each cycle of operation and the device 22 operates during the other half cycle of the current wave. tion of the igniters is controlled by an electrically operated switch A having two pairs of contact members 26 and 29 for simultaneously energizing and deenergizing the igniters 21 on the electronic devices 2| and 22. Current blocking rectifying devices 3| and 32 are provided in the control circuits for the igniters of the electronic devices 2| and 22, respectively, to prevent current from flowing through the igniter circuits except during the proper half cycle of current wave during which the respective devices are in operation.

The electronic devices. 23 and 24 are similar to the devices 2| and 22 and are so connected in the power circuit that the device 23 conducts current during one half cycle and the device 24 during the other half cycle of a current wave. The energization of the igniters 21 forthe devices 23 and 24 is controlled by a switch B having contact members 33 and 34 connected in the igniter circuits for the devices 23 and 24, respectively. Current blocking devices 35 and 36 are also provided in the igniter circuits for the electronic devices 23 and 24, respectively.

While Ihave illustrated electronic devices of the ignition-controlled type, it will be understood that any other suitable electronic device, such as a grid-controlled device, may be utilized to control the flow of current in the power circuits. As is well known in the art, the characteristics of grid-controlled electronic devices are such that the flow of current through the device may be The energiza-' 21 for the devices 2| and 22 controlled by the proper energization of the grid' controlling element of the device. Therefore, the system herein disclosed is not limited to the use of electronic devices of the type herein described.

In order that the functioning of the foregoing apparatus may be more clearly understood, the operation of the control system will now be described in more detail.

Assuming that it is desired to connect the motor In to the power source, the master controller MC maybe actuated through position I to position 2. As the controller passes through position I, the tap-changing switch is closed; however, no current will flow through the switch at this time. The energizing circuit for the actuating coil of the switch extends from the positive terminal of a battery 31 through a conductor 38, contact fingers 39 and 4|, bridged by a segment 42 on the controller MC, conductor 43, the actuating coil 44 of the switch and a conductor 45 to the negative terminal of the.

battery 31.

When the controller tion 2, the switch A on the controller MC, through conductor 41, the actuating coil 48 of the switch A and conductors 49 and 45 to the negative terminal of the battery 31.

The closing of the switch A energizes the igniter 21 of the electronic device 2| through a circuit which may be traced from the tap 5| of the transformer l5 through conductor 58, contact members 59 of the switch I, conductors 6| and 62, contact members 28 of the switch A, conductor 63, the rectifying device 3|, conductor 64, the igniter 21 and the mercury cathode 26 of the electronic device 2|, conductors 65 and 66, a portion of the preventive coil l4, conductor 61 and the transformer winding |2 to a grounded conductor 68. In this manner current is permitted to flow through the igniter .21 which produces a spark that causes an arc to be drawn between the cathode and anode of the device 2|, thereby permitting current to flow from the anode to the cathode, which will continue to flow during a half cycle of the current wave. During the other half cycle of operation, current first flows from the grounded conductor 68 through the trans: former winding l2, the conductor 61, the preventive coil l4, the conductors 66 and 69, contact members 29 of the switch A, conductor 1|,the rectifying device 32, conductor 12, the igniter 21 and mercury cathode 26 of the electronic device 22, conductors 13, 62 and 6|, the contact members 53 of the switch and conductor 58 to the tap 5| of the transformer winding l5. The energization of the igniter for the electronic device 22 functions to start operation of the device in the same manner as for the device 2| and current continues to flow through the device 22 for a half cycle.

In this manner, power is supplied to the motor II! as long as the switch A remains closed to cause the electronic devices 2| and 22 to be re-ignited at thebeginning of each half cycle. However, it will be noted that the switch l was closed before the energization of the electronic devices 2| and 22; therefore, motor load current could not flow through the switch until after the electronic devices were put in operation.

If it is desired to increase the voltage applied to the motor ID to increase its speed, the master controller MC may be actuated through position 3 to position 4, thereby first closing the switch 2 and then closing the switch B to energize the igniter circuits for the electronic devices 23 and 24.

The energizing circuit for the actuating coil of the switch 2 may be traced from the contact finger 14, which engages the segment 42 on the controller MC,through conductor 15, the actuating coil 16 of the switch 2 and conductor 45 to the battery 31.

The energizing circuit for the actuating coil of the switch B extends from a contact finger 11, which engages the segment 42 when the master controller MO is on position 4, through conductor 18, actuating coil 19 of the switch B and conductors 49 and 45 to the battery 31.

The closing of the switches 2 and B energizes the control elements for the electronic devices 23 and 24, thereby permitting current to flow through these devices in the same manner as previously described for the devices 2| and 22. During one half cycle current flows from the tap 52 of the transformer winding |5 through contact members 8| of the switch 2, conductors 82 and 83, the contact members 33 of the switch B, conductor 84, the rectifying device 35, conductor 85, the

switches.

ignlter 27 and cathode it or the electronic device 23, conductors 86 and II, the preventive coil ll, conductor 67, and the transformer winding I2 to the grounded conductor 68. The energization of the igniter 21 causes an arc to be, formed between the anode and cathode of the device 2d, thereby permitting current to flow from the anode to the cathode during the remainder of the hall cycle of the current wave. During the other half cycle, current flows through the'electronlo device 26 in the same manner as through the device 22.

The voltage applied to the motor may be still further increased by actuating the controller-MC through position 5' to position (5', thereby deenergizing the actuating coil of the switch i. However, the switoh A is opened prior to the cleanerglzation of the switch l, thereby deenergizing the control elements or the electronic devices 2! and 22 which stops thellcw of current through these respective devices at the end of the existing halt cycle of the current wave. In this manner, the switch I is prevented from interrupting the power circuit. Therefore, it does not have to be constructed for are rupturing duty, since the power circuit is interrupted by means 01 the electronic devices 2! and 22.

When the controller MC is actuated through position I to position 8', the switch 3 is first closed and then the switch A is closed to re-establish the energizing circuits for the control ele ments of the electronic devices it and 22, thereby connecting these devices to the tap 53 of the transformer winding :5 and permitting current to flow through the transformer ii in the manner hereinbeiore described.

It will be noted that the controller M is so constructed that the switch 3 is closed prior to the closing of the switch A and therefore the switch 3 does not establish the power circuit, this function being performed by the electronic devices H and 22. Likewise, the power circuit is always interrupted by means of the electronic devices 2| and 22 or 23 and 21, since the switches A and B are always opened prior to the opening of one of the tap-changing switches as the master controller MC is advanced to operate the tapchanging switches to increase the voltage applied to the motor M by connecting the transformer H to the taps to ii in sequential relation. In his manner the operation of the tap-changing switches l to l and the electronic devices 2| to 2| is coordinated to prevent the interruption of a power circuit by any one 0! the tap-changing In the modification oi the invention shown in Fig. 2, one terminal of the motor II is connected directly to the secondary winding 88 of a twowinding transformer I! which replaces the autotransformer is shown in Fig. 1. The secondary winding 88 is provided with taps II to 51, inclusive, for gradually increasing the voltage applied to the motor ll in the usual manner. 7

However, in this modification, the tap-changing operations are performed by a plurality of electronic devices 9| to ill, inclusive, which are utilized to perform'the switching operations usually performed by taphanging switches. The electronic devies shown are of the same construction as the devices shown in Fig. 1, each device having an anode 25, a. cathode 26 and an lgniter 21.

It will be noted that the electronic devices are arranged in pairs, one device of each pair being so connected that it permits current to flow during one half cycle and the other device permitting'current to flow during the other hall cycle devices is controlled The energizatlon of the or the pairs of electronic by electrically operated switches Hi to I", inclusive, each switch having a pair of contact members for establishing the control circuits for the igniter elements of a pair of electronic devices.

The operation of the switches III to ill is so controlled by means of a master controller MC that current is allowed to flow through the motor N from successive taps 5| to El on the transformer winding 88, thereby increasing the voltage applied to the motor in a manner similar to that described hereinbefore. Thus, when the controller MC is actuated to position I, the switch HI is closed to energize the control elements of the electronic devices 9! and 92, thereby permitting current to flow through these devices the preventive coll H to the motor Hi from the tap 5| of the transformer winding 88. When the controller MC is actuated to position 2', the switch H2 is closed to connect the preventive coil i i and the motor l 0 to the tapiZ on the transformer winding 88.

It will be noted that of the current wave. igniter control elements when the controller M0 is actuated to position 3', the actuating coll of the switch ill is deenergized, thereby permitting this switch to open, which deenergizes the control elements of the electronic devices 9! and 9?. to stop the flow of current through these devices, thereby disconnecting the motor it from the top 5!. In this manner the arc rupturing duty previously performed by tap-changing switches is now performed by the electronic devices. The control elements of the respective electronic 62%" vices may be energized and deenergized in the proper sequence to effect the tap-changing operations by simply operating the controller Mi) in the usual manner tocontrol the operation the switches Hi to H1, inclusive.

It will be understood-that the electronic devices may be utilized to perform tap-changing v operations on the high tension side of a transformer as well as on the low tension side, as lllus trated in Fig. 2. Thus, if desired,the tap-changing operations could be performed on the high tension side of the transformer, and an additional trans- ,former, similar to the transformer H shown in Fig. 1, may be interposed in the motor circuit to provide the desired ratio of voltage transformation. Furthermore, grid-controlled electronic devices may be utlllzed in place of the lsniter-controlled devices illustrated in Fig. 2, grid-controlled devices being well known in the art.

From the foregoing description, it is apparent that I have provided tap-changing systems in which all interrupting of power circuits is performed by electronic devices, thereby making it unnecessary for the tap-changing switches to be of a suitable construction for are rupturing duty, which permits the tap-changing switches to be of a smaller and cheaper structure. Since a. large number of tap-changing switches are usually required on a locomotive to provide the necessary control of the voltage applied to the propelling motors, considerable saving in the cost and the space required for the equipment in the locomotive can be elected by utilizing the systems herein disclosed.

Since numerom changes may be made in the above-described construction, and dlflerent cmbodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a tap-changing system, in combinationa transformer winding, a plurality oi switches for changing taps on the transformer winding, electronic devices for c ntrolling the flow of current through the tap-changing switches, and. means including current blocking rectifying devices for l() of switches for connecting said apparatus to suecessive taps on the transformer winding, electronic devices for controlling the flow or current to the power conversion apparatus, current block- I ing rectifying devices for controlling the ener- 'gization of: the

electronic devices, and control means for coordinating the operation of the electronic devices and the tap-changing switches.

4. In a tap-changin system, in combination, a

, having a plurality or tape thereon. power conversion apparatus, a plurality of switches for connecting said apparatus to successive taps on the transformer winding, electrcnic devices disposed between said apparatus and said switches for controlling the flow of current through the switches, current blocking rectifying devices for controlling the energization of the electronic devices, and control means for coordinating the operation of the electronic devices and the tap-chan g switches to prevent the switches from interruptinga power circuit.

5. In a tap-changing system, in combination, a transformer winding having a plurality of taps thereon, power conversion apparatus, a plurality of switches for connecting said apparatus to successive taps on the transformer winding, a pinrality or electronic devices for controlling the flow of current to said apparatus, said electronic devices having control elements tor controlling their operation, current blocking rectiiying devices disblocking rectifying means for, controlling the energiration of said control elements, and control means 101' coordinating the operation of the tapchanglng switches and said switching means. 

